/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/DenseMatrix.h
Elements are stored in row-major order (i.e., elements in a row are adjacent in memory). Note that FMatrix stores elements in column-major order so that we can access the columns quickly which is handy when you have rotation matrices and want the spatial axes. We don't care about that so we use the more conventional row-major indexing and matching storage.
template<int32 T_MAXELEMENTS> class TDenseMatrix